[Serusers] rtpproxy and IPv6/IPv4 translator

[CURRO_DOMINGUEZ]

Hello 

I've been installed last version of SER and rtpproxy on the same 
machine. I can register IPv4 and IPv6 users and SDP are rewritten OK.

But I would like to test a different scenario and I don't know whether 
it could be possible. The idea is

IPv6 only                     SIP proxy                    IPv4 only
SIP Proxy                     with nathelper               SIP Proxy
and registrar  ----------     and rtpproxy  -------------and registrar 

ipv6mydomain.com                                   ipv4mydomain.com    

I want to separate functions and make config files easier. And I want 
that all the calls between the two domains are through the rtpproxy.
But it presents several problems, at least, I don't find solution

- When ipv6-SER DNS lookups ipv4mydomain, it will find an A entry with 
IPv4 address. How can I specify to forward messages to intermediate 
proxy in this case? In other words, if DNS domain==ipv4 then forward to 
intermediate proxy

- Proxy with nathelper does not register users. So it just have to:
        - if message is ipv6 -->  if (af == inet6)
                        if (force_rtp_proxy("FAEI"))
                                t_on_reply("1");
        - if message is ipv4 -->  if (af == inet)
                        if (force_rtp_proxy("FAIE"))
                                t_on_reply("1");

Is it correct?.

Well, maybe could be another questions that I no see. I would thank if 
you could give me your opinion. Is there any problem to do this 
scenario? What things should I take into account? Could you give me 
some clues to write config files?

Thank you very much.

Curro